The present invention relates generally to active phased array antenna arrays for generating communications signals on multiple beams. More specifically, but without limitation thereto, the present invention relates to partitioning an active phased array antenna to reduce the peak signal power requirement of the solid state power amplifiers of each array element.
A typical active phased array antenna consists of many array elements arranged in a circular, square, or elliptical aperture. For a transmitting array, the distribution of signal amplitudes that drive the array elements may be tapered, with higher amplitude signals driving array elements near the center of the array to minimize sidelobes of the antenna pattern. The center array elements of the phased array antenna are generally the center elements for all beams. If different signals are transmitted on each beam, then the peak signal power output of the center array elements is approximately the sum of the peak signal power of all beams. If a large number of beams are used, then the maximum output power and average output power requirements of the array element power amplifiers may increase the cost of the array element power amplifiers. Also, because the center array elements are used to generate each beam, the number of phase shifters required at each of the center array elements is equal to the number of beams, and the complexity of the power combiner required to combine the output of the phase shifters at each array element is correspondingly high.
The present invention advantageously addresses the problems above as well as other problems by providing a multiple beam phased array with aperture partitioning that minimizes the required maximum output signal power of the array element power amplifiers.
In one embodiment, the present invention may be characterized as a multiple beam phased array that includes a plurality of array elements partitioned into a plurality of array element groups for forming a plurality of beams wherein each array element group has a taper center located to minimize maximum array element power for the plurality of beams.
In another embodiment, the present invention may be characterized as a method of partitioning array elements of a multiple beam phased array that includes the steps of defining a group of array elements for each of a plurality of beams and locating a taper center of each group of array elements in the multiple beam phased array to minimize maximum array element power.